Types Of Mortars Research Articles

Estimation of the Adherence of Mortars Using Ultrasound

Abstract Mortars are subjected to severe external stresses such as freezing, thawing, and drying during their lifetime. These stresses can lead to a loss of adhesion between the support and the mortar. The strength of the substrates with respect to their ability to receive a coating (mortar) is characterized in particular by the value of minimum tear resistance of the surface to be coated. In this work, the use of a non-destructive method which is both fast and easy to implement is employed to evaluate this support-mortar adhesion. The first method is based on the measurement of the velocities of the surface ultrasonic waves and the second by tearing tests using a specific dynamometer. The determination of the adhesion strength concerned two different supports (concrete beam and masonry block) coated with two types of mortar (a prepared cement mortar and a ready-to-use mortar) with two different thicknesses for each mortar (1 and 2 cm, respectively). The results of the two methods are then correlated for an estimation of the adhesion of the mortars.

English

This study aims to evaluate the influence of different additives, including natural additives such as olive oil and eggs, on repair and restoration mortars. This work enables us to verify the effects of these natural components and their impact on the physical and mechanical characteristics of various types of repair mortars. Four mortar formulations were developed and analysed: Two jointing mortars, including the control sample MF1, without additives; and two finishing mortars (plaster). The physical and mechanical analysis of these different mortar samples showed that each additive had effects on the durability, percentage of absorption and porosity of the samples, as well as on their water repelling, and waterproofing properties. The control sample MF1 had the highest content of total porosity and water absorption. In the other samples, the water absorption and porosity contents decreased with an increase in the quantity of crushed bricks. In addition, sample MF3, which contained two volumes of crushed bricks per one volume of lime and an addition of 5% olive oil, had the lowest water absorption and porosity content and the highest resistance to compression and bending. The results obtained demonstrate that the mortars with natural additives MF3 and MF4 have reduced rate of water absorption, porosity, and water absorption by capillarity than control mortars (MF1) and samples with only crushed bricks added (MF2). Key words: Repair mortar, natural additives, compatibility, crushed brick, olive oil, eggs, water repellent, durability.  

Thermal performance analysis of net-zero energy building using evolutionary algorithms

The zero-energy building, also known as Net-Zero Energy Building (NZEB), is based on the concept of an energy-efficient building that balances its total energy using solutions that aim to mitigate CO2 emissions and reduce energy use in the constructions. Energy consumption in residential and commercial buildings increased between 20% and 40% in developed countries and exceeded the industry and transportation sectors. Due to climate change, by 2050 buildings can consume 20% more energy, with energy performance being the critical element in achieving climate goals and improving energy security. The objective of this paper is to maximize the thermal comfort in an NZEB through the evolutionary algorithm PSO (Particle Swarm Optimization), a technique inspired by the collective intelligence of the animals. For this, different constructive parameters were inserted in a geometric model to identify combinations that offer greater comfort. For the optimization problem of this work, the design parameters were: block type, concrete thickness used in the solid slab, mortar type, window size, door size, and cover type. From the geometric model, an IDF file was generated for the parameterization and subsequent energy simulation of the scenarios created by the PSO in the EnergyPlus software. The exchange of materials and parameter values of the model reached lower hours of discomfort per year in comparison to results obtained in the literature.

Lightweight Pumice Mortars with Polypropylene Fiber Reinforcement

The use of porous particles as aggregates in cementitious mixes presents advantages such as reducing dead load and assisting in thermal insulation of constructions. Pumice aggregates are most commonly used because they are cheap, natural and easily obtainable. However, there are also disadvantages such as brittle behavior and decrease in strength. In this study, 0, 1 and 2 vol% polypropylene fibers (PF) having 40 micrometer diameter were used in the production of mortars containing acidic (AP) and basaltic pumices (BP) in place of calcareous sand (CS), in order to overcome these challenges. In addition to mechanical properties (compressive, flexural and splitting tensile strength), physical properties (bulk density and capillarity) and morphology of mortars (scanning electron and optical microscopy) were also investigated. The results showed that bulk density of BP mortars was about 10% lower and that of AP mortars was about 15% lower than that of CS mortars. Flexural strength of BP and CS mortars were over 7 MPa, whereas that of AP mortars were in 4–6 MPa range. Addition of 1% PF improved the mechanical properties, whereas addition of 2% PF resulted in a decrease in strength in all mortar types. The highest 1-year compressive strength was obtained by the BP sample having 1% PP fiber. Furthermore, there was a strong relationship between the strength and bulk density of mortars.

Waste ceramic as low cost and eco-friendly materials in the production of sustainable mortars

Reducing the use of natural resources and ensuring proper reuse of industrial wastes are among the most practical potential solutions for sustainable development and a cleaner environment. The generation and disposal of waste materials that cause severe ecological impacts must be inhibited. Based on these ideas, we propose the utilisation of ceramic waste, which is inexpensive, abundant, and environmentally friendly, as a partial replacement for cement and fine aggregates in the preparation of some new types of mortars. This study investigates the long-term performance, mechanical properties, and durability of a mortar comprising ceramic waste as supplementary cementitious material and ceramic particles as fine aggregates. In addition, the environmental benefits of sustainable mortar are assessed. The structure, morphology, and thermal traits of the designed mixes are characterised using scanning electron microscopy (SEM), thermogravimetric analysis (TGA), differential thermal analysis (DTA), X-Ray Diffraction (XRD), and Fourier-transform infrared spectroscopy (FTIR) measurements. The results of this study indicate that the utilisation of ceramic waste as both a binder and a fine aggregate source significantly improved the compressive strength of the mortar and provided higher resistance against adverse environmental conditions. The positive interaction between ceramic waste and fine aggregates enabled a higher level of crystalline formation and, therefore, a reduction in porosity and cracking. In summary, it was demonstrated that ceramic waste blended mortars displayed enhanced performance and energy-saving qualities, which are both technically and environmentally useful and may lead to lower construction costs and increased sustainability.

Piezoelectric cement sensor-based electromechanical impedance technique for the strength monitoring of cement mortar

Piezoelectric cement is a 0–3 type cement-based piezoelectric composite comprising 50% lead zirconate titanate (PZT) particles. Piezoelectric cement sensors, which are based on the electromechanical impedance (EMI) technique, are applied for the structural health monitoring (SHM) of cementitious materials. The compressive strength (fc) of three cement mortar types with water-to-cement ratios of 0.4, 0.5, and 0.6 were monitored for 56 days using an embedded piezoelectric cement sensor (PEC sensor). The PZT sensor was used as a counterpart in the experiments. The results indicate that the strength monitoring capability of the PEC sensor is similar to that of the PZT sensor. However, the monitoring capability of the PEC sensor is superior to that of the PZT sensor because the electrical impedance change of the PEC sensor is more evident. The PEC sensor is easy to find an effective monitoring frequency at which the conductance decreases with the age of the cementitious materials because it has the advantage of a broader frequency bandwidth that provides higher recognizing ability than the PZT. For the PEC sensor, a conductance root mean square deviation GR in a high frequency region, such as that higher than 800 kHz, can promote the reliability of mortar strength monitoring. Based on the GR value calculated at the effective monitoring frequency, the relation between fc and GR in the mortar presents a logarithmic behavior. The PEC sensor is suitable for monitoring the change in material properties, especially for cementitious materials.

Physico-Mechanical Properties of Cellulose Fiber-Cement Mortars

This paper is aimed to investigate the total sand filler replacement by two types of cellulosic fibers (bleached wood pulp - WP and recycled fibers from waste paper - RF) in cement-based mortars. Two different types of cement mortar, one with addition of finely ground limestone and other with powdered granulated slag, were mixed with fibers. The changes in consistency of fresh fiber cement mortars and development of compressive and flexural strength of mortars in dependence on hardening time up to 90 days was studied. The development of compressive and flexural strength with increasing hardening time of cellulose fiber mortars and two binders with different properties confirmed that binder mixtures containing finely ground slag and recycled cellulose fibers achieved higher values of these strength parameters. Also adhesion testing of fiber cement mortars on two substrates (ceramic fitting and aerated concrete block) after 28 days of their application showed better adhesion of cement mortars with finely ground granulated slag on the ceramic fitting surface compared to the mortars containing finely ground limestone. However, any cracks have occurred on both substrates during the maturing of mortars with slag. Based on the above facts, it can be concluded that suitable plaster mixtures for their use in the interior appear the cement recipes with both cellulose fibers (wood pulp and fibers from recycled waste paper) and with finely ground limestone.

Hyperspectral imaging features for mortar classification and compressive strength assessment

In this study, hyperspectral imagery with two computational algorithms are proposed to classify the type of mortar and assess the in-situ strength of fresh mortar in near real time. Each scanning on a mortar surface includes 30 spatial pixels selected for analysis, each assigned with a light reflectance spectrum over 400–2500 nm. Three groups of mortar samples with a water-to-cement (W/C) ratio of 0.6, 0.5 and 0.4, respectively, were cast and scanned from Day 1 to 14 of curing. Reflectance data at a wavelength range of 1920 nm to 1980 nm, associated with the O–H chemical bond, were extracted and averaged to classify the different mortar types with K-Nearest Neighbors (KNN) and Support Vector Machine (SVM) algorithms and to predict their compressive strength from a regression equation. The results showed that the average reflectance increased with time due to water molecules reaction during curing process. The KNN classification model with K = 5 had a prediction accuracy of 70% to 75%, and the SVM classification model with C = 1000 and σ = 10 showed a prediction accuracy of approximately 90%. Therefore, the SVM classification algorithm is recommended for use in mortar classification. The compressive strength is well correlated with the average reflectance with a coefficient of over 0.98.

Effects of Temperature on Fluidity and Early Expansion Characteristics of Cement Asphalt Mortar.

In order to solve the problems of the sudden loss of fluidity and low expansion rate of CAM I (cement asphalt mortar type I) in a construction site with high environmental temperature, this paper studies the effect of temperature on the fluidity, expansion ratio and pH value of CAM I. The mechanism of action was analyzed by IR (infrared spectrometry), SEM (scanning electron microscopy) and other test methods. The results showed that a high temperature accelerates aluminate formation in cement paste. Aluminate adsorbs emulsifiers leading to demulsification of emulsified asphalt, and wrapped on the surface of cement particles, this causes CAM I to lose its fluidity rapidly. The aluminum powder gasification reaction is inhibited, resulting in an abnormal change in the expansion ratio. Based on findings, the application of an appropriate amount of superplasticizers can effectively improve the workability and expansion characteristics of CAM I at a high temperature.

Influence of Exposure to Elevated Temperatures on the Physical and Mechanical Properties of Cementitious Thermal Mortars

Thermal mortars incorporating insulating aggregates are a possible solution to ensure good thermal performance and thermal comfort in buildings due to their low thermal conductivity coefficient. Under some circumstances, namely for particular in-service conditions in industrial applications and/or accidental actions (such as fire), it is important to quantify the retention of their properties after exposure to elevated temperatures, however this information is not yet available in the literature. This study aims to characterize the physical and mechanical behavior of thermal mortars incorporating expanded clay, granulated expanded cork and silica aerogel as aggregates after exposure to elevated temperatures. To this end, five types of mortars were produced in laboratory conditions—three thermal mortars, one reference sand mortar and one sand mortar with admixtures—and then exposed to different elevated temperatures (from 20 °C to 250 °C) in a thermal chamber. After thermal exposure, the following properties were assessed: bulk density; ultrasonic pulse velocity; dynamic elasticity modulus; dynamic shear modulus; Poisson coefficient; compressive strength; and thermal conductivity. The results obtained show that residual properties present a very high dependence on the reactions that take place in the cement paste when the mortars are exposed to elevated temperatures. After such exposure, all mortars with thermal insulating aggregates were able to maintain their insulating characteristics, but experienced internal damage and degradation of their mechanical properties. Results obtained also showed that insulating aggregates allowed to produce mortars with higher aggregate-cement paste compatibility at elevated temperatures compared to conventional mortars, resulting in less micro-cracking of the mortar, and leading to lower reductions in thermal conductivity with increasing temperature.

Assessment of the Mechanical Parameters of Resin Composites with the Addition of Various Types of Fibres.

The article describes tests of epoxy mortars after the addition of fibres. The fibres were a substitute for sand in the amount of 0, 1, 2, 3, 4 and 5% by volume, respectively. Three types of mortar were obtained, containing polypropylene, glass and carbon fibres, respectively. Statistical analyses (ANOVA) were carried out to assess the impact of fibre content on the mechanical properties of mortars. Brittle fracture toughness was also tested using the Cracked Straight Through Brazilian Disc method. The addition of each type of fibre improved the assessed parameters. Based on the obtained research results, and also due to availability and price, the most advantageous seems to be the production of composites containing the addition of polypropylene fibres.

Lime and cement mortar consolidation by ammonium phosphate

The present study investigates the strengthening ability and the compatibility of two different ammonium phosphate solutions used for consolidation of mortars based on slaked lime, natural hydraulic lime or cement, to resemble historic and modern mortars. After impregnation for 24 h, new calcium phosphate phases were detected in all types of mortar. New calcium phosphates induced significant mechanical consolidation, with only slight alterations in the pore system and in water transport properties. In lime-based mortars (initially white) no color alteration was visible after treatment, while colored mortars experienced some color change when the more concentrated phosphate solution was used.

Comparison between physical–mechanical properties of mortar made with Portland cement (CEMI) and slag cement (CEMIII) subjected to elevated temperature

The use of blast furnace slag during the manufacture of cement is assumed to mitigate CO2 emissions. Generally, the amount of blast furnace slag in the slag cement (CEMIII) ranges between 36 % and 95 %. Slag cement is suitable for the production of all concrete classes, such as the large-scale civil engineering projects (roads, tunnels, bridges). In the case of tunnels, evaluating the performance of concrete exposed to high temperatures will be of great interest. This paper deals with the mechanical properties of cement pastes and mortars made with an ordinary Portland cement (CEMI) and slag cement (CEMIII) subjected to temperatures up to 650 °C. For this purpose, The test specimens were cured for 90 days and then subjected to four different temperatures (160, 300, 400 and 650 °C) at 1 °C/min. Following the 1 h of thermal load, the specimens were examined once their temperature cooled down to room temperature. Measurements were taken for mass loss, permeability, residual compressive strength and modulus of elasticity for each temperature.The test results demonstrated that permeability increases with temperature, and it follows an exponential type formula for both types of mortar. Where there is more loss of permeability in MIII mortars than in MI mortars.The residual compressive strength of all specimens increased up to 160 °C and decreased with further increase in temperature. This decrease is more significant when the temperature exceeds 400 °C. For all heating temperatures, the samples made from the slag cement (CIII and MIII) show higher residual compressive than those made with Portland cement (CI and MI). Furthermore, it was found that at all exposure temperatures the modulus of elasticity of all samples was more reduced compared to the compressive strength. In conclusion, we can say that when using slag cement, the samples show a good mechanical behavior (compressive strength and modulus of elasticity) at high temperatures and also for permeability.

Study of the Compressive Strength of Mortars as a Function of Material Composition, Workability, and Specimen Geometry

In the present work, the statistical dispersion of the mortar compressive strength as a function of the geometric parameters of the specimens as well as the effect of the mortar workability difference on the compressive strength was investigated. For this purpose, specimens were prepared for six types of mortars: two conventional mortars in the proportions of 1 : 1 : 6 and 1 : 2 : 9 of cement, hydrated lime, and sand, respectively, two with clay replacing lime, and two with marble waste in place of lime. The results confirm the difference between the results found for the two geometries due to the differences in the heights of the molding layers and show that the workability of the mortar modifies the resistance properties, especially in the cylindrical mold where the molding of the specimens is more complex. By comparing the differences between the destructive test results and those defined by the Finite Element Modeling (FEM) for conventional mortars, it was clear that the effect of excess material in the sample during the compression tests did not change the strength properties studied. This facilitates the performance of the assay as specimens may be used excessively on the side without the need for sample rectification.

Low cost system for measuring the evolution of mechanical properties in cement mortars as a function of mixing water

The water/cement ratio is a determining factor when making mortars since it depends on the adequate hydration of the cement so that the final mass reaches the desired strengths and the adequate workability of the material for subsequent handling. This paper presents a low-cost system based on resistive sensors of the Arduino platform, capable of reliably quantifying and in real-time, the loss of mix water that occurs in mortars through the hydration of the cement and the evaporation itself of water from its mix in a fresh state. Two types of aggregates have been used: natural and mixed recycling, and two dosages for each of them with cement/aggregate 1:3 and 1:4 ratios, where it has been possible to corroborate thanks to the sensor developed the differences in setting between these two types of mortars, and how the evolution of their mechanical properties over time is conditioned by the variation of the water content of mix. In this way, it has been possible to validate the measurement equipment developed to be used in the study of the evolution of setting in conglomerate materials.

Evaluation of the physical-mechanical properties of cement-lime based masonry mortars produced with mixed recycled aggregates

This study investigated the physical-mechanical effects of cement-lime mortars containing recycled aggregate of construction and demolition waste (CDW). The natural aggregate (NA) was replaced by volume at 25%, 50%, 75% and 100% by mixed recycled aggregate (MRA) obtained from the CDW crushing. Five types of mortars were prepared with a volumetric ratio of 1:1:6 (cement, lime and aggregate) and water/binder ratio based on the fixed consistency of 260 mm. The effects of MRA on fresh and hardened mortars’ properties were analyzed. The results were analyzed using a one-way ANOVA. MRA incorporation improved most of the physical-mechanical properties of mortars tested, except for hardened bulk density, water absorption and porosity. In the long-run, mechanical strengths significantly increased in all compositions, especially those with higher percentages of MRA. The results obtained showed that the use of MRA in masonry mortars is an alternative to reduce the generation of waste and consumption of natural resources.

Study the behavior of Slurry infiltrated fibrous concrete (SIFCON) under impact loading

SIFCON, as a type of fiber reinforced concrete (FRC), has a unique and superior properties in the areas of both ductility and energy absorption and the impact resistance is recognized as one of the significant properties of SIFCON.The main object of present study is to determine the influence of SIFCON mortar type and fiber volume fraction on the behavior of SIFCON under impact loading. For SIFCON mortar, supplementary cementitious materials [Class F fly ash (FA) and silica fume (SF)] were used as a partial replacement by weight of cement. The percentage of FA replacement was (20%) and of SF replacement was (10%). Hooked end steel fibers were used with different fiber volume fraction (6, 8.5, and 11) %, the test was carried out using disc specimen (152 mm diameter by 63 mm thick). The test results were compared with those of fiber reinforced mortar (FRM) containing 2% fiber volume fraction, as a reference (control) mix. The test results show that in general, there is a significant improvement in impact resistance of all SIFCON mixes with increasing fiber volume fraction. SIFCON mix containing SF and FA and 11% volume fraction exhibited the highest impact resistance, and the energy required for completing failure was increased by 11.87 times, when compared with the control mix at 90 days.

Observation of crack initiation zone in brick masonry couplets under compression using X-ray microfocus computed tomography and digital image correlation

The constituent materials of masonry include different brick and mortar types with various properties. The difference in the stiffness properties of these materials influence the observed failure modes under compression. The general theory of the failure mechanisms in brick masonry under compressive loading relies on the difference between the relative elastic modulus of brick and mortar. The aim of this paper is to visually examine the above theory about the behaviour of masonry under compression using a high-resolution X-ray micro-CT scanner. Additionally, full-scale couplets have been tested under compression with the application of stereo-vision digital image correlation (DIC). The failure progression in masonry which evolves from the initiation of micro cracks, over the propagation into macro cracks has been clearly evidenced. Overall, the results from DIC positively confirm the observation from X-ray micro-CT.

Observation of crack initiation zone in brick masonry couplets under compression using X-ray microfocus computed tomography and digital image correlation

The constituent materials of masonry include different brick and mortar types with various properties. The difference in the stiffness properties of these materials influence the observed failure modes under compression. The general theory of the failure mechanisms in brick masonry under compressive loading relies on the difference between the relative elastic modulus of brick and mortar. The aim of this paper is to visually examine the above theory about the behaviour of masonry under compression using a high-resolution X-ray micro-CT scanner. Additionally, full-scale couplets have been tested under compression with the application of stereo-vision digital image correlation (DIC). The failure progression in masonry which evolves from the initiation of micro cracks, over the propagation into macro cracks has been clearly evidenced. Overall, the results from DIC positively confirm the observation from X-ray micro-CT.

The Effect of Activator to Binder Ratio on the Compressive Strength of Fly Ash Based Geopolymer Mortar in Sulphate Environment

One of the significant characteristic material needed to consider is durability. Sulphate ion contained in soil is one of aggressive agents that could cause degradation of concrete members which led to loss of compressive strength. The current research is to elaborate the effect of activator to binder ratio on the compressive strength of the fly ash based geopolymer mortar in the sulphate environment. Two different types of geopolymer mortar were casted i. e. mortar made of 100% fly ash and mortar contained 95% fly ash + 5% slaked lime. The fly ash used in this research is classified as F fly ash from the Mpanau power plant the variation of activator to binder ratio of 0. 40; 0. 50; and 0. 60, and water/solid ratio variations of 0. 32, 0. 34 and 0. 36. The composition of sulfuric acid was by 5% of the sample volume. Geopolymers mortar compressive strength test is conducted on the immersed samples in a solution of 5% sulfuric acid with age of 0, 7, 14, 28, 56, and 84 days, respectively. The compressive strength test results showed that the highest compressive strength of geopolymers mortar (resistant to sulfuric acid attack) was geopolymers mortar made from fly ash with activator to binder ratio 0. 60, water / solid ratio 0. 32, and percentage of lime to binder 5% at the age of 84 days.